The present invention pertains to a shifting device with a gearshift lever for an automatic transmission of a motor vehicle with an unlocking mechanism for unlocking the gearshift lever with a manual actuating element, wherein the gearshift lever is movable in at least one shift gate between at least two different shift positions and can be locked in these shift positions at least partially as a function of different vehicle configurations.
Such shifting devices with gearshift levers are used in automatic transmissions for motor vehicles, and such automatic transmissions usually have at least one automatic gate, in which the gearshift lever can be shifted between the positions xe2x80x9cPxe2x80x9d for park position, xe2x80x9cRxe2x80x9d for reverse, xe2x80x9cNxe2x80x9d for a neutral position, which brings about the uncoupling of the transmission from the vehicle, and xe2x80x9cDxe2x80x9d for travel in the forward direction with gears shifted automatically. Additional shift positions are also provided in most cases in addition to the xe2x80x9cDxe2x80x9d position in order to select different transmission programs. In addition, there is also a Tiptronic gate in some cases, in which the gears of the transmission can be selected manually.
In order not to move the gearshift lever accidentally and thus to avoid either damage to the vehicle or another danger, a manual actuating element in the form of, e.g., an unlocking knob is arranged in most prior-art gearshift levers, by which knob an intentional unlocking of the shifting device is performed, so that, e.g., the gearshift lever can be shifted from position xe2x80x9cPxe2x80x9d to position xe2x80x9cR.xe2x80x9d Incorrect conditions [sicxe2x80x94typo in German original for word meaning xe2x80x9coperating errorxe2x80x9dxe2x80x94Tr.Ed.], which could unintentionally lead to the destruction of the transmission, e.g., due to putting in the reverse at a high forward speed, are also avoided correspondingly.
One example of such a shifting device with a gearshift lever for an automatic transmission of a motor vehicle has been known from the applicant""s German Patent Specification DE 195 13 809 C1. This patent specification discloses a gearshift lever, with a knob arranged at the top end of the gearshift lever, a locking bar guided axially at the gearshift lever and a displaceable unlocking knob, which can be actuated manually and by means of which the locking bar can be raised by reversing the force by pushing in the unlocking knob and which thus eliminates the locking of the gearshift lever.
Another similar shifting device with a gearshift lever for an automatic transmission is shown in the applicant""s yet unpublished patent application DE 198 29 173. This gearshift lever likewise has a knob at the top end, an axially guided locking bar and a locking knob that can be moved by hand for actuating the locking bar. The transmission of forces between the locking knob and the locking bar takes place via fixed teeth on an elliptical contour, so that a favorable course of the manual forces is obtained during the actuation of the unlocking knob.
To avoid operating errors of the vehicle, modern shifting devices have a system for blocking the unlocking mechanism of the gearshift lever in certain vehicle configurations, e.g., a so-called key lock system. For example, the parking brake shall be prevented with the key lock from being actuated without an ignition key. This means that the gearshift lever cannot be moved from its xe2x80x9cPxe2x80x9d position due to blocking of the unlocking mechanism until the ignition key is correspondingly inserted. Consequently, this system prevents the vehicle from rolling away unintentionally.
Such a system becomes problematic when the driver is not familiar with the function of the key lock system in conjunction with the automatic transmission and attempts to bring about the unlocking of the gearshift lever by applying a correspondingly strong force on the unlocking knob, even though the key lock system actually blocks the movement of the gearshift lever. If the unlocking knob is actuated forcibly to unlock the gearshift lever in such a situation despite the blocking of the unlocking knob, this usually leads to the destruction of one of the force-transmitting elements of the unlocking mechanism, as a result of which the ability of the shifting means to function may be at least compromised.
The object of the present invention is therefore to provide a shifting device with a gearshift lever for an automatic transmission of a motor vehicle in which the actuation of the manual actuating element to unlock the gearshift lever does not bring about any destruction in the gearshift lever and in the entire shifting device even when stronger forces are applied in the case of an intended locking of the gearshift lever.
The object of the present invention is accomplished by the features of claim 1. Embodiments are the subject of the subclaims.
The above-described destruction of the unlocking device of the gearshift lever or of parts thereof by misactuation can be avoided if the force transmission between the manual actuating element for unlocking the gearshift lever and the locking bar is designed such that in the case of an intended locking of the unlocking mechanism by a key lock system, actuation of the manual actuating element brings about only an inward deflection of a force transmission element beginning from a certain force applied, without all elements of the unlocking mechanism, especially an axial movement of the locking bar, having to be absolutely brought about [sicxe2x80x94Tr.Ed.]. At the same time, the force transmission between the manual actuating element and the locking bar shall have a sufficiently firm coupling, so that unlocking of the gearshift lever will take place due to the actuation of the manual actuating element in a permitted vehicle configuration.
It is correspondingly proposed that a shifting device with a gearshift lever for an automatic transmission of a motor vehicle with an unlocking mechanism for unlocking the gearshift lever with a manual actuating element, where the gearshift lever is movable in at least one shift gate between at least two different shift positions and can be locked at least partially in these shift positions as a function of different vehicle configurations, be improved such that a spring-tensioned force transmission element is provided in the unlocking mechanism.
Such a design of the shifting device advantageously causes that not all the forces that possibly occur at the manual actuating element will be passed through the unlocking mechanism, as a result of which it is also possible to make the mechanical parts lighter and thus less expensive.
The spring-tensioned force transmission element may preferably act as a force-transmitting connection member between the manual actuating element and the rest of the unlocking mechanism.
It is achieved as a result that even though the actuation of the manual actuating element leads to a movement of the unlocking mechanism in the normal case, the spring-tensioned element of the force transmission element undergoes an inward deflection in case of blocking of the unlocking mechanism, as a result of which only a movement of the manual actuating element, but no movement or rupture will occur in the unlocking mechanism, and destruction of the shifting device is thus avoided.
At least part of the unlocking mechanism may consist of a locking bar, which can be moved by the manual actuating element.
Such a spring-tensioned force transmission element may be arranged, e.g., pivotably around an axis, so that a movement of the manual actuating element approximately at right angles to the axis of the locking bar can bring about a simultaneous axial movement of the locking bar.
It is advantageous for the spring-tensioned force transmission element to have a spring support and a curved leg spring, which is braced thereon and is clamped in the pivoting direction on two sides at one of its legs and on one side at its other leg. This causes that during a movement of the force transmission element, the leg spring can be deformed beginning from a certain force without the existing kinematics being damaged.
To predefine a certain force beginning from which the spring-tensioned force transmission element prevents the movement of a locked locking bar without destruction, provisions may be made for the leg spring of the force transmission element to have a pretension, so that the feeling of the force coupling being too soft in the unlocking mechanism of the gearshift lever will not arise in normal operation during the actuation of the manual actuating element.
Provisions are made in a special embodiment of the force transmission element for the leg spring surrounding the pivot axis at least partially. Furthermore, the spring support itself is mounted pivotably.
The coupling of the forces between the spring-tensioned force transmission element and the manual actuating element can be brought about by embodying a pivotably and displaceably movable connection, preferably via the engagement of a pin or a roller on one of the two elements with a groove or an elongated hole on the respective other element.
For the force transmission between the spring-tensioned force transmission element and the locking bar, the locking bar may, furthermore, have a stop or an engagement, with which the spring-tensioned force transmission element, especially a leg of the leg spring, comes into contact or engagement.
It is obvious that a reverse design of the force transmission between the manual actuating element, especially an unlocking knob on a gear shift handle grip and the locking bar, can also be embodied without going beyond the scope of the present invention. It is also possible to use a coil spring instead of the leg spring described if the kinematics between the manual actuating element and the unlocking mechanism is correspondingly adapted.
For example, the locking bar or another force-transmitting element of the unlocking mechanism can be made spring-tensioned in the direction of its force transmission, so that a type of telescopic effect will occur beginning from a predetermined force and damage to the mechanical elements is avoided as a result of this as well. If, e.g., the locking bar of one of the prior-art shifting devices is modified such that it is made telescopically spring-tensioned, possibly with a coil spring between two telescope arms, the desired effect can also be achieved while maintaining the otherwise known shifting device.